1. Field
Embodiments of the present invention relate to an electronic control brake system for vehicles which prevents residual frictional force generated between a disc and pads.
2. Description of the Related Art
In general, a vehicle is provided with a plurality of wheel brakes, each of which includes a caliper device including a disc and a pair of pads to brake a front wheel or a rear wheel to decelerate or stop the vehicle, a booster forming brake hydraulic pressure and transmitting the brake hydraulic pressure to the wheel brakes and a master cylinder, and thus, when a driver presses a brake pedal, the hydraulic pressure formed on the booster and the master cylinder is transmitted to pads of the wheel brakes, and the pads press the disc, thus generating braking force. However, when brake pressure is greater than a road surface state or frictional force of the wheel brakes generated by the brake pressure is greater than braking force generated from tires or a road surface while the driver presses the brake pedal to allow the vehicle to be in a braking force increasing state or a braking force maintaining state, slippage of the tires on the road surface occurs.
Recently, in order to effectively prevent such slippage to provide strong and stable braking force and to facilitate driving operation, brake systems, such as an anti-lock brake system (ABS) preventing slippage of wheels during braking, a traction control system (TCS) preventing excessive slippage of wheels during sudden start or sudden acceleration of a vehicle, and a vehicle dynamic control system stably maintaining the driving state of a vehicle by controlling a brake by combining an ABS and a TCS if the vehicle is not adjusted according to driver intention by force applied from the outside during high-speed driving of the vehicle, have been developed.
These conventional brake systems for vehicles include in common a modulator block (i.e., a hydraulic unit) including a plurality of solenoid valves, accumulators, a motor and pumps to control brake hydraulic pressure transmitted to wheel brakes, and an ECU to control electrically operated parts. The ECU senses a vehicle speed through respective wheel sensors disposed on front wheels and rear wheels, and thus controls operation of the respective solenoid valves, motor and pumps.
In the conventional brake systems, a disc of the wheel brake and a pair of pads pressing both sides of the disc may minutely come into contact due to partial abrasion without generation of brake pressure during driving. Contact between the disc and the pads generates residual frictional force and thus causes acceleration and driving loss.